Process for the intramolecular dehydrogenation of aromatic ring systems



. By the desisnationfcholl reacuenfia procees has become'known according to which" aromatic nuclei are linked together with aid of aluminium chloride, while splitting offarorriatical1yhound hydrogen. Reference is madein this connection to Scholl" and] Seer, LiebigsAnna'le'n, vol; 394,

page 111 (11912) "and tewpagesfiacga Jer Georg Krz'inzlein, Aluminiumchlorid in der org anischen Che-rulepublishedi'by charmer B'erlinJEThis' process is advantageously carried batsman; hy-. drogen acceptors. These {may ,essentially a'ccelerate the course ofthe reac-tionaridincrease ,the yield; If the aluminium "chloride fusion is I conducted in the presence or xygeu as hydliqfieii acceptor, good yields are obtained only wlieri the as is intensivelyldistributed inth'efh "'m'eltl nf involves great difliculty on a largescale and necessitates,

apparatus." Dimculties satisfactory distribution of gas, however;

specially constructed 7 which are not without importance alsoarieowing to thegreatly increased sublimation of alu-e .minium chloride in the current of, oxygen, 11in,-

stead of oxygen other hydrogen acceptors are,

mswitlerlandg; asaignora to the .flrm society 6!- ;Chemlcal, Industry in Basle, Basel, Switzerland Q Application July 20,"1938, Serial No.

02. In SwihcrlandJJulyl23, 193T I l 1 n 1 me; and haioenatioasare than as far sits Max .sible; 2 Suitable hydrogen; acceptors {or use in this invention are, for instance meta -dinitrobeniene,

meta-nitrobenzel esillfonic acid, .picric acid, di-

nitronaphthalenes, 1' 1 nitronaphthalenef sulfonic 1 acids, .nitrochloronaphthalenes, nitroanthracene- The invention; is; p1 value; in all products with which; the Scholli reaction, with 1, formation of raromatic six membered carbon,- rings, leads on principle also to the desired result. The process l is particularly advantageous when applied to compounds containingpketone groups. It, may thereiore be, used; for; ntample the synthesis of the pdibenzpyrenequinones Iron; 1;5-, naphthalene on =from :Bz l benzoylbenranthrone, -=ofipyranthrone, of naphtho and anthradian-v throne, of l ibenzanthrone, ,of phenanthrenequitnone, of yiolanthrone ,and .is'oviolanthrone and dibenzoylderivatives of these,

products, further in the synthesis of perylene and derivatives thereof, and

, I the like.

- 'I'he following examples illustrate the invenused, for instance potassium permanganate; manlaanese dioxide, lead peroxide, cerium dioxide,

vanadium pentoxide, arsenic pentoxide,- barium"- eroxide, ierric oxide, ferric chloride, ,cupric U v p sisting o! 242 parts 0! aluminiumchloride and 58 oxide, mercuric oxide; sodium nitrite; nitrate, sulfur or selenium, the technical conduct of the process is extraordinarily simplified but at the same time the yields obtainable in the presence of oxygen are no longer achieved. Moreover, the purity of the final product'when such oxidizing agents are used leaves much to 'be desired, because the h dro en chloride which is y g dilute hydrochloric acid. From the reaction maproduced in the fusion is decomposedywhereby the halogenating effect generally occurring in such reactions is muchi'avoured. This halogenation is still more intensive when products such as chlorine, bromine or sulfuryl chloride are used as hydrogen acceptors. T

This invention relates to a process of this kind in which there are used as hydrogen acceptors ultra-compounds having in addition to the nitrogroup at least one other negative substituent, for instance a nitro-, sulfoor hydroxy-group. In comparison with the use of oxygen, such nitrocompounds, in consequence of their solubility in the fused mass, shorten to a strong degree the duration of the reaction 'and'at the same time permit, the fusion to be effected in apparatus of simple construction. As compared with the use of theother inorganic acceptors, nitro-compounds permit the production of the final products in good yield, even approximately quantitaportions. The blue mass "tion, the parts being byweightz 25 w Example 1 To a molten mass capable of being stirred. conparts 'of sodium :chloride at a temperature of 0. there are added 20 parts of 1:5-dibenzoylnaphthalene and then in the course of 4 hours 13 parts of meta-dinitrobenzene in small is then decomposed with water and the organic material is freed from aluminium chloride by extraction with boiling terial there is obtained in approximately quantitative yield by vatting the 3:4z8z9-dibenzpyrenequinone-fi: 10. 7 Example 2 20 parts of 1:5-dibenzoylnaphthalene are introduced into a melt of 300 parts or sodium-alu minium chloride at 160 465 C. and' there are then added in the course ofi 4 hours in small portions '19 parts of sodium meta-iiitrobenzenesulfonate. After stirring for 2 hours 't the same temperature the mass is decomposed-with water and extracted with boiling dilute hydrochloric acid. Attenvatting the remaining product there is ob- .-.tained 3:4:8z9-dibenzpyrenequinone-5gig in a yield of 30 90 per cent of the theoretical Example 3 Into a iniittui'e'oi 3 parts of benzanthro'he and ,56 parts of benzoyl chloride there are introduced at a temperature below 100 C. 300 parts of aluminium chloride. The whole is stirred for one hour at. 145-150 C. and there are then added in the course of 8 hours 19 parts of sodium metanitrobenzenesulfonate, and stirring is continued for a further hour at the same temperature. After the usual working up, the product is treated with sodium hyp chlorite solution until the yellow-brown color s passed to a brilliant orange. The product diss lves in concentrated sulfuric acid to a carmine s lution having a brilliant moss green fluorescence This latter arises from impurities and is rem ved by extraction with benzene. There is thus obtained in quite good yield 3:428:9-dibenzpyrene undone-5:10. l5

Ea: mple 4 40 parts of tetrabenkoylpyrcne (obtainable by y heating to boiling for 3 hours a mixture of f1 part of :pyrene, 5 parts of acetylene tetrachloride, 4 parts of benzoyl chloride and 0.5 part of sublimed ferric chloride) are dissolved in a melt of 600 parts of sodium-aluminium chloride at 125-150 C. There is then added carefullylto the melt 52 parts of meta-dinitro-benzene. The mass is stirred until it has acquired a violet color. The melt is then worked up in the usual manner and\ the dyestufi produced is purified by vatting. There is obtained in good yield a brown-yellow powder soluble in concentrated sulfuric acid to a 3 red-violet solution and dyeing cotton yellow tints.

Example 5 hours. When the formation of. dyestuff is com- 40 plete the fusion is worked up analogously as in as hydrogen acceptor nitrobenzene Example 3. The yield of the dyestuii amounts to over '70 per cent of the theoretical.

What we claim is:

1. Process for the intramolecular dehydrogenation of aromatic ring systems by means of aluminium chloride according to the Scholl reaction with aid of hydrogen acceptors, comprising using as hydrogen acceptor aromatic nitro-compounds which in addition to the nuclearly bound nitro-group contain at least one other negative 'substituent. v

2. Process for the intramolecular dehydrogenation of aromatic ring systems by means of aluminium chloride according to the Scholl reaction with aidof hydrogen acceptors, comprising using as hydrogen acceptor aromatic nitro-compounds of the benzene series which in addition to the 'nnclearly bound nitro-group contain at least one other negative substituent.

. 3. Process for the intramolecular dehydrogem, ation of aromatic ring systems by means of aluminium chloride according to the Scholl reaction with aid of hydrogen acceptors, comprising using as hydrogen acceptor aromatic nitro-compounds of the benzene series which in addition to the nuclearly bound nitro-group contain a sulfo-group.

4. Process for the intramolecular dehydrogenation of aromatic ring systems by means of aluminium chloride according to the Scholl reaction with aid of hydrogen acceptors, comprising using -meta-sulfonic acid.

5. Process for the intramolecular dehydrogenation of aromatic ring systems by means of aluminium chloride according to the Scholl reaction with aid of hydrogen acceptors, comprising using as hydrogen acceptor 2:4:6-trinitro-1-hydroxybenzene.

EDUARD MOERGELI. KARL KRAUER. MAX BOMMER. 

